Dielectric heating gun



Jan. 3, 1956 G. s. MOGILNER DIELECTRIC HEATING GUN 2 Sheets-Sheet 1 Filed March 16, 1953 0 Q 9 w y 0; H

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ATTQZNEI Jan. 3, 1956 G. s. MOGILNER 2,729,732

DIELECTRIC HEATING GUN Filed March 16, 1953 2 Sheets-Sheet 2 Gzaeaz Sjlfa/z wee,

I N V EN TOR.

United States Patent DIELECTRIC HEATING GUN George S. Mogilner, Los Angeles', Calif. Application March 16, 1953, Serial No. 342,354

4 Claims.v (Cl. 219-10.75)

The present invention relates generally to high frequency apparatus, and is more particularly concerned with. dielectric heating apparatus which is particularly adapted, among other uses, for the dielectric heating of glueused in the securing of members into intimate relationship.

The invention is especially concerned with the applicatorbymeans of which a high-frequency electric field may be set up betweensuitable electrodes adapted to be applied against plywood or other dielectric materials was to cause heating of glue for quickly setting and securing the dielectric members together.

Briefly the applicator of the present invention is in the-form of a so-called.gun which embodies spaced electrodes having connection with tuning means which maybe eitherinductive or capacitive, but in the present instance is capacitive. The gun has apistol grip handle by means of which the electrodesmay beapplied.

Energy is supplied from a suitable source to the gun through a coaxial connection cable, and novel means are provided for adjusting the tuning, such means-being conveniently located with respect torthe pistol grip, so that the'operator may utilize a finger of the hand which engages the pistol grip for varying the tuning of the device for securing maximum power.

In utilizing a gun of this character, the environment is such that the parts for tuning the electrical circuit, particulariy the condensenis-subjectto the accumulation of dust, sawdust, and other foreign particles which are in the air, and as a result present a possibility of breakdown due toarcing. It is therefore one object of the invention to provide a dielectric gun in which the condenser is positioned further away from the electrodes out of an exposed position, and wherein the condenser is more fully protected by the housing of the device.

Afurther object is to provide a novel construction in the tuning condenser, wherebysliding contacts will be eliminated, and corona tendency with concomitant arcing will be substantially decreased to the end that greater reliability and more efficient operation may be obtained.

Still another object is to provide novel means for adjusting the condenser to vary the tuning of'the device, such tuning means including a movable digitally operable member which is conveniently positionedadjacent the pistol grip handle, and so located that it is unnecessary for theoperator to release his grip onthe handle in order to manipulate the tuning mechanism: with the same hand that grips the handle. A single hand operative gun is thus provided, and it is unnecessary as in conventional devices of this character as heretofore fabricated to utilize two hands in order to grip the handle and adjust the tuning of the device.

- Still-another object is to provide visually indicating means which are positioned in such a location that projecting parts around the outer surface of the housing of the device will be substantially eliminated.

Further objects of the invention will be brought out in the following part of the specification, wherein detaileddescriptionis for thepurpose of fully disclosing the invention without placing limitations thereon.

Referringto the-accompanying drawings, which are forillustrative purposesonly:

Fig. 1 is a perspectiveview of dielectric heating apparatusembodyingmthe features of the present invention;

Fig. 2 is alarge vertical section through the apparatus, taken substantially on line 2-2 of Fig. 1;

Fig. 3 is a-horizontal section, taken substantially on line 3-3 of Fig. 2;the-view being rotated Fig. 4 is a.verticalsectional'view transversely of the apparatus showing details of the condenser plates, taken substantially on line 4-4=of Fig. 2; and

Fig. 5 is a fragmentary sectional view showing details of the condenser adjusting means, taken substantially on line 5-5 of Fig.2.

Referring generally to the drawings, for illustrative purposes, theapparatus of the presentinvention is disclosed in Fig. 1 as comprising in the main a rectangular box-like housing 10 of sheet metal or other suitable material. This housing is open on its forward side and supports in spaced relationfrom the housing a pair of spaced electrodes 11 and 12, in this instance being in the form Tot-fiat elongate metallic bars. On theopposite side of the housing, the housing is closed by a wall 13 which has secured thereto and extending outwardly therefrom a pistol grip handle, as generally indicated by the numeral 14. This handle forms apart which the operator may conveniently grip in one hand and by means of which the apparatus may be easily manipu lated for positioning and holding the electrodes against the dielectric material during use. The pistol grip has mountedthereon a push button switch control 15 which is electrically connected by means (not shown) to the source of high frequency, and by means of which the energization of the source may be controlled at will.

As more clearly shown in Figs. 2 and 3, each electrode is. supported by spaced pins 16 on the forward sideof a metallic cross-bar 17, this cross-bar being connected at each end as by screws 18 to an insulating arm 19. The inner. end of each. arm 19 is secured .as by bo1ts=20 to the associated side wall of the housing 10, a spacing bar 21 being-interposed between the bar and housing wall to inwardly space the insulating arms from the wall.

Within the housing 10, at a position approximately midway between the front and back of the housing, a pair of side rails 22 and 23 of insulating material are supported in laterally spaced relation and forwardly of the wall 13 by means of spacer posts 24-24 which are secured atone end as by a screw 25 to the wall 13, and at its other end as by a screw 26 to an end of.the side rail. The rails 22 and 23 provide insulatingsupports for the tuning elements of a tuning circuit which connects with the electrodes 11 and 12, as will hereinafter be explained.

One of the elements of the tuned circuit comprises a condenser having a pair of fixed plates 27 whichare positioned with their surfaces in a common plane, and are laterally spaced apart and provided with confronting edge notches 28 as shown clearly in Fig. 4. Each plate is supported in a position parallel with one of the side rails and is secured thereto by mounting bolts 29-and 30, a spacer sleeve 31 being provided in each case to space the associated condenser plate 27 with respect to the associated side rail. In each case, the bolt 30 is made of greater length than the bolt 29 in-order to serve as a terminal for the opposite ends of a secondary coil 32 of an air core transformer 33 mounted on the opposite side of the side rails 22 and 23 fromthe condenser plates 27. The bolts 30 therefore support the secondary coil, which is of sutficiently large sized wire to be self-sustaining and hold its shape, and also serve to interconnect the ends of the secondary respectively with the fixed condenser plates 27. Jumper connectors 34 interconnect each terminal bolt 30 and the associated end of the transformer secondary coil 32 with a cross-bar 17, thus providing circuit connections with the electrodes 11 and 12.

The transformer 33 has a single turn primary winding 35 which is positioned intermediate the ends of the secondary coil and surrounds the turns thereof in spaced relation. Connection leads are brought out from the primary winding between the confronting edges of the condenser plates 27-27, at the position containing the notches 28. These leads, as indicated at 36 and 37 are further carried through an opening 38 in a third associated condenser plate 39 of substantially rectangular shape, which is supported in spaced confronting overlapping relation to the fixed plates 27 and arranged for swinging movement about its lower edge in directions normal to its surface.

As shown in Figs. 2 and 4, the condenser plate 39 is secured along its bottom edge margin to one edge of a strip 40 of resilient flexible material, the upper marginal edge of which is clamped between the associated edge of the condenser plate and a retaining strip 41 secured by a series of rivets 42. The opposite edge of the strip 40 is supported in the spacer posts 24 adjacent the housing bottom. It will be observed that the strip 40 is longitudinally deformed intermediate its edges to provide a line of bend 43 and stress the strip in such a direction as to normally bias the movement of the condenser plate 39 in a clockwise direction, as shown in Fig. 2, so that it has a tendency to move from its full line position to the dotted line position, as shown.

With the arrangement of tuning elements as described in the foregoing, it will be observed that the transformer windings are more closely positioned with respect to the electrodes 11 and 12, while the condenser plates are positioned further back in the housing so that the condenser plates will be more fully protected from dust, sawdust, dirt and other foreign matter which would tend to increase any tendency towards arcing, and moreover by utilizing a condenser construction as just described, the corona effect and concomitant arcing tendency is materially reduced so that the parts will operate at greater efficiency. Not only does the strip 40 provide a mounting for the condenser plate 39, but it also connects this plate with the grounded side of the high frequency source by connecting the condenser plate through the metallic spacer post 24 with the wall 13.

Unique means are provided for varying the position of the condenser plate 39 by a mechanism which is readily operable by a digit of the operators hand which grips the pistol grip 14 of the apparatus. For this purpose, a tubular member 44 is mounted for swinging movement by connecting it at one end to the movable wing 45 of a hinge 46 which has its other Wing 47 anchored to the wall 13. The outer end of the tubular member 44 is adapted to bear against the plate 39 so as to form an abutment which may be moved to adjustably vary the position of the condenser plate.

The position of the tubular member 44 is arranged to be varied by means of a digitally operable member 48 which is rotatably supported upon a bracket 49 secured to the wall 13 as by suitable screws 50. The member 48 is rotatably supported on a vertically extending pivot screw 51 which threadedly engages the bracket 49 and has its head portion bearing against a friction washer 52 so as to retain the member 48 against inadvertent P movement from an adjusted position. As shown in Fig. 3, the member 48 has a sector shaped portion 53 bounded by a serrated edge 54 and having circinnferentially spaced edges 55 and 56 adapted to abut the wall 13 and thus limit the movement of the member in opposite directions, and consequently define the limits of movement of the tubular member 44. On the opposite-side from the portion 53, the member 48 is provided with a projection 57 having a cam edge 58, this projection extending through an opening 59 in the wall 13 and having the cam edge in engagement with a projecting finger 60 which is integrally formed with the movable wing 45 of the hinge so that rotative movements of the member 48 will act to adjust the plate 39 of the condenser and tune the high frequency circuit connected to the electrodes so as to obtain maximum power when used with cliiferent materials and diflerent thicknesses.

High frequency energy is supplied through a coaxial cable 61 having an inner conductor 62 which is connected through an insulated terminal 63 supported on the wall 13 with the lead 36 of the primary Winding of the transformer 33. The outer shield 64 of the coaxial cable is grounded and is connected with a connecting terminal 65 having electrical connection with the wall 13 and the lead 37 of the transformer primary winding.

A pilot lamp 66 is positioned in the upper portion of the hollow pistol grip structure for indicating the condition of energization of the apparatus. The wall of the pistol grip is provided with spaced opening". or windows 67 which are separated by a lamp protective bar 68. The lamp is energized from a tertiary coil 69 which is supported in inductively coupled relation to the transformer secondary winding coil 32. It will be observed that with this construction, the housing 10 is devoid of projecting knobs, etc. which would possibly interfere under some conditions with the utilization of the gun.

Various modifications may suggest themselves to those skilled in the art without departing from the spirit of my invention, and, hence, I do not wish to be restricted to the specific form shown or uses mentioned, except to the extent indicated in the appended claims.

I claim:

1. In dielectric heating apparatus containing a tuned circuit: a wall member; a pair of spaced insulated electrodes supported in spaced relation to said wall member; a tuning condenser on one side of said wall member comprising a pair of plates; means supporting said plates in fixed insulated relation to said wall and laterally spaced apart with their surfaces lying substantially in the same plane; a third plate in spaced confronting relation to said pair of plates having an opening therein; a flexible member electrically connecting the third plate with said wall member and movably supporting it for swinging movement about an edge thereof in a direction normal to its surface; a transformer positioned between said condenser and said electrodes including a primary coil and a secondary coil, the secondary coil having one end electrically connected to one plate of said pair and one of said electrodes, and its other end electrically connected to the other plate of said pair and the other electrode, the primary coil having connection leads extending between said pair of plates and through said opening in the third plate; and digitally operable means mounted on said wall for moving said third plate.

2. In dielectric heating apparatus containing a tuned circuit: a wall member; a tuning condenser on one side of said wall member comprising a pair of plates; means supporting said plates in fixed insulated relation to said wall and laterally spaced apart with their surfaces lying substantially in the same plane; a third plate in spaced confronting relation to said pair of plates having an opening therein; a flexible member electrically connecting the third plate with said wall member and movably supporting it for swinging movement about an edge thereof in a direction normal to its surface; a transformer having a primary coil and a secondary coil, the secondary coil having its ends respectively connected to said pair of plates, and the primary coil having leads extending between said pair of plates and through said opening in the third plate; connection terminals for said leads supported on said wall, one of said terminals being insulated as to the wall and the other being electrically connected thereto; and digitally operable means mounted on said wall for moving said third plate.

3. In dielectric heating apparatus containing a tuned circuit; a wall member; a tuning condenser on one side of said wall member comprising a pair of plates; means supporting said plates in fixed insulated relation to said wall and laterally spaced apart with their surfaces lying substantially in the same plane; a third plate in spaced confronting relation to said pair of plates having an opening therein; a flexible member electrically connecting the third plate with said wall member and movably supporting it for swinging movement about an edge thereof; a coil positioned on the opposite side of said pair of plates from said third plate with connection leads extending between said pair of plates and through said opening in the third plate; connection terminals for said leads supported on said wall, one of said terminals being insulated as to the wall and the other being electrically connected thereto; and digitally operable means mounted on said wall for moving said third plate.

4. In dielectric heating apparatus containing a tuned circuit: a wall member; a tuning condenser on one side of said wall member comprising a fixed plate and a movable plate; means supporting the fixed plate in insulated relation to said wall member; a flexible resilient member electrically connecting the movable plate with said wall member and supporting the plate for swinging movement about an edge thereof in a direction normal to its surface; a pistol grip handle secured to said wall and ex tending from the side thereof opposite said condenser; an elongate member pivoted at one end on said wall member for swinging movement, the other end of said elongate member being positioned to abut said movable plate; and a cam adjacent the pivoted end of said elongate member operable to swingably adjust the angular position of said elongate member and vary the position of said movable plate in its swinging movement, said cam having a portion positioned for operating engagement by a digit of an operators hand while gripping the pistol grip handle.

References Cited in the file of this patent UNITED STATES PATENTS 1,538,472 Crosley May 19, 1925 1,616,093 Stein Feb. 1, 1927 1,891,283 Kilgour Dec. 20, 1932 2,465,102 Joy Mar. 22, 1949 2,596,636 Wright May 13, 1952 

